923: Mainline

Now, you must augment your definition so that your form becomes a view capable of supplying information to a model. Your augmentation involves two steps:

• You connect a listener to the text fields and buttons. That listener calls the form's setters, thus maintaining the form's instance variables.
• You arrange for the entire form to produce events and to activate listeners that are connected to the form.

Thus, there are two listener levels:

• A lower-level listener, connected directly to text fields and buttons, operates inside the form, maintaining the form's instance variables.
• A higher-level listener, connected to the form itself, is in charge of fetching information from the form, using the form's getters, and relaying that information to a model.